Heat-Dissipation Design and 3D Printing of Ternary Silver Chalcogenide-Based Thermoelectric Legs for Enhancing Power Generation Performance.

Thermoelectric devices have received significant attention because of their potential for sustainable energy recovery. In these devices, a thermal design that optimizes heat transfer and dissipation is crucial for maximizing the power output. Heat dissipation generally requires external active or passive cooling devices, which often suffer from inevitable heat loss and heavy systems. Herein, the design of heat-sink integrated thermoelectric legs is proposed to enhance heat dissipation without external cooling devices, realized by finite element model simulation and 3D printing of ternary silver chalcogenide-based thermoelectric materials. Owing to the self-induced surface charges of the synthesized AgBiSe2 (n-type) and AgSbTe2 (p-type) particles, these particle-based colloidal inks exhibited high viscoelasticity, which enables the creation of complex heat-dissipation architectures via 3D printing. Power generators made from 3D-printed heat-dissipating legs exhibit higher temperature differences and output power than traditional cuboids, offering a new strategy for enhancing thermoelectric power generation.

Unlocking the Potential of Porous Bi2Te3-Based Thermoelectrics Using Precise Interface Engineering through Atomic Layer Deposition.

Porous thermoelectric materials offer exciting prospects for improving the thermoelectric performance by significantly reducing the thermal conductivity. Nevertheless, porous structures are affected by issues, including restricted enhancements in performance attributed to decreased electronic conductivity and degraded mechanical strength. This study introduces an innovative strategy for overcoming these challenges using porous Bi0.4Sb1.6Te3 (BST) by combining porous structuring and interface engineering via atomic layer deposition (ALD). Porous BST powder was produced by selectively dissolving KCl in a milled mixture of BST and KCl; the interfaces were engineered by coating ZnO films through ALD. This novel architecture remarkably reduced the thermal conductivity owing to the presence of several nanopores and ZnO/BST heterointerfaces, promoting efficient phonon scattering. Additionally, the ZnO coating mitigated the high resistivity associated with the porous structure, resulting in an improved power factor. Consequently, the ZnO-coated porous BST demonstrated a remarkable enhancement in thermoelectric efficiency, with a maximum zT of approximately 1.53 in the temperature range of 333-353 K, and a zT of 1.44 at 298 K. Furthermore, this approach plays a significant role in enhancing the mechanical strength, effectively mitigating a critical limitation of porous structures. These findings open new avenues for the development of advanced porous thermoelectric materials and highlight their potential for precise interface engineering through the ALD.

Fabrication and Characterization of Electrospun Cu-Doped TiO2 Nanofibers and Enhancement of Photocatalytic Performance Depending on Cu Content and Electron Beam Irradiation.

Titanium dioxide (TiO2) is a widely studied material with many attractive properties such as its photocatalytic features. However, its commercial use is limited due to issues such as deactivation in the visible spectrum caused by its wide bandgap and the short lifetime of photo-excited charge carriers. To overcome these challenges, various modifications could be considered. In this study, we investigated copper doping and electron beam treatment. As-spun TiO2 nanofibers were fabricated by electrospinning a TiO2 sol, which obtained viscosity through a polyvinylpyrrolidone (PVP) matrix. Cu-doped TiO2 nanofibers with varying dopant concentrations were synthesized by adding copper salts. Then, the as-spun nanofibers were calcined for crystallization. To evaluate photocatalytic performance, a photodegradation test of methylene blue aqueous solution was performed for 6 h. Methylene blue concentration was measured over time using UV-Vis spectroscopy. The results showed that Cu doping at an appropriate concentration and electron-beam irradiation showed improved photocatalytic efficiency compared to bare TiO2 nanofibers. When the molar ratio of Cu/Ti was 0.05%, photodegradation rate was highest, which was 10.39% higher than that of bare TiO2. As a result of additional electron-beam treatment of this sample, photocatalytic efficiency improved up to 8.93% compared to samples without electron-beam treatment.

Upcycling green carbon black as a reinforcing agent for styrene-butadiene rubber materials.

This study reports the effects of recovered carbon black (produced in a clean and sustainable way) as a reinforcing agent on the physicochemical properties of a styrene-butadiene rubber (SBR) matrix. SBR-based composite materials are prepared with recovered green carbon black (GCB), and these are thoroughly compared to the composite materials containing conventional virgin carbon black (VCB) (produced by the incomplete combustion of petroleum products). The GCB-SBR composite materials generally show detectably inferior properties compared to the VCB-SBR composite under the same preparation conditions due to the limited functionality of the GCB filler. However, the introduction of a small amount of crosslinker, acrylate-functionalized POSS (polyhedral oligomeric silsesquioxane), into the GCB-SBR composite materials effectively enhances the overall physical properties, including the tensile strength, fracture elongation, and thermal stability. The degree of the crosslinking efficiency, thermal stability, and mechanical properties of the composite materials are optimized and thoroughly examined to demonstrate the possibility of replacing typical VCB with GCB, which can allow for upcycling the inexpensive and ecofriendly carbon black materials as effective reinforcing fillers.

Effects of the Immobilization of the Upper Extremities on Spatiotemporal Gait Parameters during Walking in Stroke Patients: A Preliminary Study.

BACKGROUND: The purpose of this study was to investigate the effects of upper extremity immobilization and consequent walking speed on spatiotemporal gait parameters in stroke patients with hemiparesis. METHODS: The following variables were assessed or measured in 29 stroke patients: age, height, weight, disease duration, Korean version of the Mini-Mental State Examination (MMSE-K), Berg balance scale (BBS-K), functional gait assessment (FGA-K), cause of the disease (type of lesion), and hemiparetic side. The measurement of gait was performed using two pressure plates of 1.5 m to create a 3 m walking distance and leaving 1.5 m of extension at both start and end, to ultimately create a 6 m walking distance that the patient could walk through. The following gait patterns were randomly selected based on card draws: self-selected walk speed (SW), self-selected walk speed with immobilized upper extremities (SWI), fast walking (FW), and fast walking with immobilized upper extremities (FWI). Each patient was assessed for four different gait patterns, with three measurements per pattern (12 gait measurements in total). RESULTS: While there were significant differences in the stride length, step width, velocity, and step length of the paretic side between self-selected walk speed (SW) and SWI, FWI did not show significant changes in any of the tested parameters. CONCLUSIONS: Immobilization of the upper extremities may affect walking at self-selected walk speeds. A comprehensive training program including upper extremity movement should be established for gait rehabilitation. Clinical Trial Registration. This trial is registered at http://cris.nih.go.kr/cris.

Enzymatic Synthesis of Glucosyl Rebaudioside A and its Characterization as a Sweetener.

Rebaudioside A was modified via glucosylation by recombinant dextransucrase of Leuconostoc lactis EG001 in Escherichia coli BL21 (DE3), forming single O-α-D-glucosyl-(1″→6') rebaudioside A with yield of 86%. O-α-D-glucosyl-(1″→6') rebaudioside A was purified using HPLC and Diaion HP-20 and its properties were characterized for possible use as a food ingredient. Almost 98% of O-α-D-glucosyl-(1″→6') rebaudioside A was dissolved after 15 days of storage at room temperature, compared to only 11% for rebaudioside A. Compared to rebaudioside A, O-α-D-glucosyl-(1″→6') rebaudioside A showed similar or improved acidic or thermal stability in commercial drinks. Thus, O-α-D-glucosyl-(1″→6') rebaudioside A could be used as a highly pure and improved sweetener with high stability in commercial drinks. PRACTICAL APPLICATION: The proposed method can be used to generate glucosyl rebaudioside A by enzymatic glucosylation. Simple glucosyl rebaudioside A exhibited high acid/thermal stability and improved sweetener in commercialized drinks. This method can be applied to obtain high value-added bioactive compounds by enzymatic modification.

Kakkalide and irisolidone alleviate 2,4,6-trinitrobenzenesulfonic acid-induced colitis in mice by inhibiting lipopolysaccharide binding to toll-like receptor-4 and proteobacteria population.

The flower of Pueraria lobata (family Fabaceae) has been clinically used in traditional Chinese medicine to counteract symptoms associated with drinking alcohol and liver injury and to alleviate inflammatory diseases. Its major constituent kakkalide is metabolized to irisolidone by gut microbiota. This research study was undertaken to understand the anti-colitis mechanism of kakkalide and irisolidone in vitro and in vivo. Kakkalide and its metabolite irisolidone inhibited lipopolysaccharide (LPS)-stimulated NF-κB activation and TNF-α expression in macrophages. They also inhibited LPS-induced phosphorylation of IRAK1 and TAK1 and activation of NF-κB by inhibiting the binding of Alexa Fluor 488-conjugated LPS in vitro. Orally administered irisolidone or kakkalide alleviated colon shortening and myeloperoxidase activity in mice with 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. Their treatments also protected epithelial cell disruption and infiltration of CD11b+/CD11c+ cells in the colon. Furthermore, they suppressed TNBS-induced expression of M1 macrophage markers TNF-α, CD80, CD86, and Arg2 expression while the expression of M2 macrophage markers Arg1, CD163, CD206, and IL-10 was induced. They also suppressed the fecal Proteobacteria population. Overall, the anti-colitic effects of irisolidone were superior to those of kakkalide. Kakkalide and its metabolite irisolidone inhibited inflammation in vitro and in vivo by inhibiting LPS binding to toll-like receptor 4 and gut proteobacteria population.